Ipomoea batatas is a member of the morning glory family Convolvulaceae. This species is grown worldwide and it exhibits a wide range of plant forms and colors. Grown by farmers worldwide, the cultivated members of Ipomoea batatas are commonly produced for consumption of their nutritious, enlarged storage roots. This contrasts with potatoes (Solanum tuberosum), which produce an edible tuber derived from an underground stem, which is similar in structure to the above ground stems.
Presently, two dominant sweetpotatoes are produced in the United States, ‘Covington’ (U.S. Plant Pat. No. 18,516) and ‘Beauregard’ (unpatented). ‘NC05-198’ provides an improvement over ‘Covington’ in that it produces plants that are ready earlier in the planting season, and does not produce round sweetpotatoes when planted in cooler soils. ‘NC-05-198’ is also tolerant to internal necrosis, a physiological defect in sweetpotato associated with the production of necrotic lesions in the internal portions of the storage root, which can be a significant problem in ‘Covington’ under certain conditions. ‘NC05-198’ provides an improvement over ‘Beauregard’ in consistency of shape and higher “packout” of the more valuable No. 1 class of sweetpotatoes and greater stability across different environments.
Lineage. ‘NC05-198’ originated from bulked botanical seed harvested from the open pollinated female parent ‘NC97A-45’ (not patented) in the 2004 Streptomyces soil rot (SSR) polycross breeding nursery. The SSR breeding nursery was planted in Clayton, Johnson County, N.C. (NC). The 15 genotypes present in the SSR nursery were randomly mated during the course of a four month flowering period in which seed was harvested from the 15 genotypes present in the nursery; therefore the male parent of ‘NC05-198’ is unknown. Three patented male parents (‘L96-117’ U.S. Plant Pat. No. 15,038, ‘Bienville’ U.S. Plant Pat. No. 15,380; and ‘Evangeline’ U.S. Plant Pat. No. 19,710) were in the nursery, and therefore, represent potential pollen sources.
Seedlings from the SSR breeding nursery were planted in greenhouses in Clinton, N.C. in March of 2005. A single cutting was taken from each seedling and planted in the field in May in Kinston N.C. and selected as a “single hill selection” on August 30th. A “single hill selection” includes all of the good quality storage roots derived from the single plant cutting, typically 2-15 storage roots with 2-10 being saved for propagation the next year.
Asexual Reproduction. ‘NC05-198’ has been propagated as vegetative stem cuttings and/or storage root derived stem cuttings derived from adventitious sprouts emanating from its storage roots since its original selection in August of 2005. After further cycles of selection for horticultural traits and disease screenings, ‘NC05-198’ was subjected to meristem tip culture and subsequent tissue culture maintenance-to eliminate viruses and pathogens via meristem tip culture. The characteristics disclosed herein for ‘NC05-198’ have remained stable and the plant has reproduced true to type through successive generations of asexual propagation.